Pultrusion processes traditionally use wet resin to impregnate dry fibers prior to the fibers being pulled through a pultrusion die. Pultrusion of pre-impregnated (prepreg) fiber/resin combinations is more difficult, due to adhesion of the resin to the die and the much longer cure cycle times.
Certain aerospace prepreg material systems are pre-qualified for use in military applications. These material systems are typically not usable in pultrusion processes due to the difficulty of pultruding prepreg material systems.